Control for automatic transmission

ABSTRACT

In an electrical control for an automatic transmission, including a throttle position signal generator and having vehicle speed as well as throttle position as input signals and an optimum selection of gear range as an output, the improvement wherein the throttle position signal generator comprises a magnet operatively connected to a throttle valve, a plurality of magnetically energized switches connected with a circuit including resistors and a source of electric energy for generating a stepped throttle position signal voltage.

Unite States Patent Arai et a1.

[ 1 Sept. 4, 1973 l l CONTROL FOR AUTOMATIC TRANSMISSION [75] Inventors:Hiroshi Arai; Takakazu Mori, both of Toyota-shi, Japan [73] Assignee:

[22] Filed:

Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota-shi, Japan Nov. 29, 1971[21] Appl. No.: 203,092

Related US. Application Data [62] Division of Ser. No. 80,116, Oct. 12,1970, Pat. No.

[52] U.S. Cl. 307/116, 335/206 [51] Int. Cl. H0111 36/00 [58] Field ofSearch 307/116, 106, 117,

References Cited UNITED STATES PATENTS Wheable et a1 307/115 3,052,1349/1962 Worster 74/866 2,870,648 l/l959 Gill .1 74/866 X PrimaryExaminer-J. V. Truhe Assistant Examiner-M. Ginsburg Attorney-Stevens,Davis, Miller & Mosher [57] ABSTRACT 9 Claims, 9 Drawing Figures vPATENTED 3.757. 133

SHEET 2 (IF 5 FIG. 4 5

u g E v5 \I N4- N3- N2 5 .5 5 Z 0 I l l FULL THROTlZE 9/ 92 93 mama/vFULL) CLOSED THROTTLE ANGLE 9 THROTTLE P05/7/0/v T/B I/VSM/SS/O/V CUTPUTSHAFT VOL 7A 65 l/EH/CLE SPEED VOL 746E En VEHICLE SPEED 1 CONTROL FORAUTOMATIC TRANSMISSION This is a division, of application Ser. No. 80,116, filed Oct. 12, 1970, now U.S. Pat. No. 3,707,097, issued Dec. 26,1972.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to a an apparatus for detecting throttle positions of an engine,and particularly to one used for an electrical control for an automatictransmission of the kind used in automotive vehicles having multipleforward speed ranges, a neutral range, and a reverse range.

DESCRIPTION OF THE PRIOR ART To control an automatic transmission havingmultiple forward speed ranges, a neutral range, and a reverse range, atleast three basic control signals are necessary. These signals are: anengine operated parameter signal, a vehicle speed signal, and a manualgear range selector signal. Most commonly, the engine operated parametersignal is represented by a throttle position signal, and the vehiclespeed signal is represented by a transmission output shaft speed signal.When a manual gear range selector which selects one range out of severalranges including a forward range, a neutral range, and a reverse rangeis set to the forward range by a driver, forward gear range shifts of anautomatic transmission are controlled by the throttle position signaland the vehicle speed signal according to a predetermined shift patternwhich is described in terms of throttle position and vehicle speed.

When a hydraulic medium is used exclusively, the

control system becomes very complex. Therefore, efforts are continuouslybeing made to replace signal generating and processing means of thecontrol system, which is operated hydraulically, with electricallyoperated means to make the control system simpler. This electricallyoperated means is hereinafter called an electrical control circuit.

The prior art electrical control circuit utilizes a potentiometer or amulticontact switch, each linked with an engine throttle valve and alsoconnected with a battery or another kind of electric energy generatorand resistors, if necessary, to produce a voltage which corresponds tothrottle position and is, therefore, the throttle position signal. Thisvoltage is, in general, called a throttle voltage.

However, the potentiometer and the multicontact switch have twodisadvantages: one is that they lack durability due to friction contactbetween the moving part linked with the engine throttle valve and thestationary part, and the other is that they often produce distortedsignals caused by vibrations at contact points, which are transmittedfrom the vehicle body or the engine.

When the potentiometer is utilized, the throttle voltage changescontinuously as the throttle position changes. Usually a relationshipbetween the throttle voltage and the throttle position is linear.However, when the multicontact switch is utilized, the throttle voltagechanges discontinuously as the throttle position changes, and isexpressed by a stepped line in relation to the throttle position.

In a shift pattern diagram which is described in terms of throttleposition and vehicle speed, a shift line is a line which corresponds toshifts between adjacent gear ranges, and an upshift line and a downshiftline are lines which correspond to upshifts and to downshifts betweenadjacent gear ranges respectively. In the same diagram an upshift lineand a downshift line corresponding to each other are an upshift line anda downshift line which correspond to upshifts and downshifts between thesame adjacent gear ranges. Also in the same diagram shift lines arecontinuously smooth sloped lines, usually sloped straight lines, intheir major portions or in all portions when the potentiometer is used,but the shift lines are stepped lines when the multicontact switch isused. Further in the same diagram, a space or spaces must be providedbetween the upshift line and the downshift line corresponding thereto toprovide hysteresis in the electrical control circuit for the preventionof oscillation between the gear ranges. When the potentiometers isutilized, if the space along the vehicle speed axis between the upshiftline and the downshift line corresponding thereto is provided, the spacealong the throttle position axis between the two is inherently provided,because the shift lines are sloped. This means that no oscillationoccurs when shifts occur due a to change of the position of a pointrepresenting the condition of vehicle speed and throttle position in theshift pattern diagram along thevehicle speed axis or the throttleposition axis or both. However, when the multicontact switch isutilized, even if the space along the vehicle speed axis between theupshift line and the downshift line corresponding thereto is provided,the space along the throttle position axis between the two is notautomatically provided, because the shift lines are stepped lines.Therefore, when the multicontact switch is utilized, the electricalcontrol circuit which provides the space along the throttle positionaxis between the upshift line and the downshift line correspondingthereto as well as the space along the vehicle speed axis between thetwo becomes more complicated than the electrical control circuit whichprovides the space only along the vehicle speed axis between the upshiftline and the downshift line corresponding thereto. Therefore, when themulticontact switch is utilized, usually only the space along thevehicle speed axis between the upshift line and the downshift linecorresponding thereto is provided to avoid the complexity of thestructure and mechanism of the electrical control circuit at thesacrifice of the oscillation between gear ranges at the portions of theshift pattern diagram where no space is provided between the upshiftlines and the downshift lines corresponding thereto.

Although the electrical control circuit employing a multicontact switchand providing only the space along the vehicle speed axis has the above-mentioned disadvantage, it has a big advantage over the electricalcontrol circuit employing a potentiometer. This advantage is that thestructure and mechanism of the former becomes very simple as comparedwith the latter.

SUMMARY OF THE INVENTION The control for an automatic transmission ofthis invention utilizes the same structure and mechanism as the controlfor an automatic transmission (hereinafter called the simple control)which employs a multicontact switch as a distinct part of the throttleposition signal generator incorporated in the electrical control circuitof the control and which provides only the space along the vehicle speedaxis between the upshift line and the downshift line correspondingthereto in the predetermined shift pattern diagram without providing thespace along the throttle position axis between the upshift line anddownshift line corresponding thereto and, further, which is the simplestin the structure and mechanism among the controls for automatictransmissions described below: (1) one which uses a hydraulic mediumexclusively; (2) one which uses a potentiometer as a distinct part ofthe throttle position signal generator incorporated in the electricalcontrol circuit of the control and provides the space between thecorresponding upshift and downshift lines along the vehicle speed andthrottle position axes; (3) one which uses a multicontact switch as adistinct part of the throttle position signal generator incorporated inthe electrical control circuit of the control and provides the spacebetween the corresponding upshift and downshift lines along the vehiclespeed and throttle position axes; and (4) the simple control beingherein described, except the multicontact switch which is replaced by anew switch device which is a part of this invention to take advantage ofsimplicity of the simple control and, therefore, to take advantage ofincreased reliability and reduced production cost as the result of thesimplicity.

The switch device of this invention comprises magnetic means operativelyassociated with a throttle valve of an engine driving the automatictransmission and a plurality of magnetically energized switch meansdisposed in a spaced relationship to each other and to the magneticmeans. The magnetically energized switch means is energized by themagnetic means to close its electric circuit. More specifically, themagnetic means is a magnet mounted on a rotatable disc operativelyconnected to the throttle valve, and the magnetically energized switchmeans is a reed switch which is a switch comprising a container usuallymade of glass, a pair of metal reeds disposed in the container in aconfronting manner and having an overlapped portion near the tipsthereof with a small gap therebetween. When the reed switch is energizedby a magnetic flux formed by the magnet and passing through the reeds,the reeds contact with each other, thereby closing the switch. When thereed switch is de-energized, the read switch opens due to the resilientforce of the reeds.

When the simple control is modified by replacing the multicontact switchof the simple control with the switch device of this invention, themodified simple control has a big additional advantage while maintainingthe advantage of simplicity of the original simple control. Thisadditional advantage is that the modified simple control has, due to thehysteretic characteristic of the switch device 'of this invention, thespace along the throttle position axis between the corresponding upshiftand downshift lines as well as the space along the vehicle speed axisbetween the corresponding upshift and downshift lines, for prevention ofoscillation between gear ranges when shifts occur along the throttleposition axis as well as the vehicle speed axis.

Another advantage of the modified simple control of this invention isthe prevention of transmission of disturbances caused by vibrations fromthe vehicle body or the engine into the throttle position signal byutilizing the hysteretic characteristic of the switch device of thisinvention.

Still another advantage of the modified simple control of this inventionis an improvement in the durability of the switch device incorporated inthe throttle position signal generator by the elimination of directcontact between the moving part linked with the throttle valve and thestationary part of the switch device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of athrottle voltage generating circuit of this invention.

FIG. 2 is a plan view of a switch device of this invention.

FIG. 3a and 3b taken together show a shape and magnetic poles of apermanent magnet incorporated in the switch device shown in FIG. 2.

FIG. 3b is a view A of FIG. 3a.

FIG. 4 is a diagram showing a relationship between throttle voltage Eand throttle angle 0 obtained from the throttle voltage generatingcircuit shown in FIG. 1, a component of which is theswitch device shownin FIG. 2.

FIG. 5 is a block diagram of an electrical control circuit for a threeforward speed automatic transmission.

FIG. 6 is a diagram of a vehicle speed signal voltage E, which isproduced by a speed sensor connected with a frequency converter shown inFIG. 5 and is proportional to transmission output shaft speed,consequently to vehicle speed.

FIG. 7 is a transmission shift pattern diagram in terms of throttlevoltage versus vehicle speed voltage.

FIG. 8 is a diagram of the same shift pattern as shown in FIG. 7, drawnin terms of throttle angle 0 versus vehicle speed V.

DESCRIPTION OF THE PREFERRED EMBODIMENT It is intended that the controlof this invention be applicable to a large variety of automatictransmissions, particularly those in which shifting can be carried outby the operation of brakes and clutches. However, the specificembodiment described herein is designed to apply toa three forward speedtransmission. The example of the three forward speed transmission is theone which is described in detail in a copending U.S. patent applicationSer. No. 874,934 (filed Nov. 7, 1969; Inventors: Wakamatsu et al.), nowU. S. Pat. No. 3,675,511, issued July 11, 1972 and assigned to the sameassignee of this invention.

The electrical control circuit .of this invention (the electricalcontrol circuit of the modified simple control) .is described below inconjunction with the three forward speed transmission disclosed inparent Ser. No. 80,116 (now U.S. Pat. No. 3,707,097) with reference toFIGS. 9 and 10 thereof.

First of all, means for generating the throttle position signal (thethrottle voltage) which is called a throttle position signal generatoror a throttle voltage generating circuit is described below.

The throttle voltage generating circuit of this invention comprises theswitch device of this invention.

In carrying out this invention various types of switch devices, such asa rotary type (a type in which the permanent magnet rotates as athrottle valve rotates), or a sliding type (a type in which thepermanent magnet slides as a throttle valve rotates) can be utilized.The specific embodiment described herein is a switch device of a rotarytype with four reed switches, designed to apply to a three forward speedtransmission.

Examples of reed switches which can be used in this invention are thosemanufactured by Western Electric Co., U.S.A., having code numbers 224A,2378 and G29, although in this particular embodiment Fujitsu reedswitches manufactured by Fujitsu Co., Japan are utilized.

Referring to FIG. 1 the throttle voltage generating circuit illustratedcomprises a battery 1 whose electromotive force is E and whose negativeterminal is grounded, a permanent magnet 2, (which is drawn by phantomlines) whose magnetic poles and movement are shown by N and S and atwo-head arrow, respectively, which is linked with an engine throttlevalve (not shown in the drawing), read switches 3, 4, 5, and 6,resistors R R R R and R respectively, another resistor R,, an end ofwhich is grounded, and a voltage output terminal 7.

The switch device as shown in FIG. 2 comprises a case 8 made of plasticin which the reed switches 3, 4, 5, and 6 are mounted, and a rotor 9which is located inside the case 8 and connected with an engine throttlevalve (not shown in the drawing) by means of an arm 10 and a throttleshaft 11. A permanent magnet 2 whose shape and magnet poles are shown inFIG. 3a and 3b is mounted in one portion of the rotor 9 to enable eachone of the reed switches to close its corresponding electric circuitwhen the switch is energized by the magnetic flux of the magnet 2 as themagnet passes each switch. The switches are de-energized when themagnetic flux is sufficiently reduced by the movement of the magnet awayfrom the switches.

Still referring to FIG. 2 a situation in which a throttle angle, whichis an angle indicating throttle position, is consecutively increasedfrom the fully closed throttle position is first considered below.

The reed switch 3 is located in a position where its electric circuit isclosed when a throttle angle measured from the fully closed throttleposition becomes a predetermined angle 0,. Likewise, the reed switches4, 5, and

6 are located in positions where their electric circuits are closed whenthe throttle angle becomes predetermined angles 0 0 and 0,,respectively.

When the throttle angle is increased from zero (the fully closedthrottle position) by depressing an accelerator pedal but does not reach0,, all reed switches are off and, therefore, the throttle voltagemeasured at the voltage output terminal 7 is where E,,, throttle voltagewhen the throttle angle is increased from zero but is less than 0,.

When the accelerator pedal is further depressed to obtain -a throttleangle between 0, and 0,, the reed switch 3 is on and consequently thethrottle voltage is where E throttle voltage when the throttle angle isincreased from an angle smaller than 0, to an angle between 0, and 0,.

Likewise, when the accelerator pedal is further depressed to obtainthrottle angles between 6, and 0 between 0,, and 0,, and between 0, and0 (the angle of the full throttle position), the reed switches 3 and 4are on, 3, 4, and 5 are on, and 3, 4, 5, and 6 are on, respectively.Consequently, the throttle voltages become respectively 1 1 1 sier awhere E throttle voltage when the throttle angle is increased from anangle smaller than 0, to an angle between 0 and 0 1 1 1 1 1 E E RZ RI Ewhere E throttle voltage when the throttle angle is increased from anangle smaller than 0, to an angle between 0, and 0 A situation in whichthe throttle angle is consecutively decreased is next considered.

Even if the throttle angle is decreased to 0, from 0 (the full throttleposition) by releasing the accelerator pedal, reed switch 6 does notbecome deenergized due to hysteresis of the reed switch. Only when thethrottle angle becomes a certain fixed angle smaller than 0,, that reedswitch 6 will be de-energized. That fixed angle is hereinafterdesignated as 0,. In other words, when the throttle angle is greaterthan 0, while it is being decreased from 0 the throttle voltage isalways E-,,. The range between 0, and 0, is a hysteresis range.

This hysteresis range is determined by the characteristics of the reedswitch, the location of the reed switch in relation to the permanentmagnet, and the magnetmotive force of the permanent magnet.

Likewise, fixed throttle angles where the reed switches 5, 4, and 3become de-energized while the throttle angle is being decreased from 0,continuously by releasing the accelerator pedal are designated as 0 0and 0,, respectively. Again in other words, in the range between 0, and0,, between 0,, and 0,, between 0 and 0,, and between 0, and zero (thefully closed throttle position) the throttle voltages are E E E and Erespectively. The foregoing relationship between the throttle angle 0and the throttle voltage E, is shown in FIG. 4.

In contrast to the above, the throttle voltage generating circuit whichreplaced the reed switches with a multicontact switch produces thethrottle voltages E E E E and E in the ranges between 0,, and 0,,between 0, and 0,, between 0, and 0,, between 0, and 0,, and between 0,and zero, respectively, when the throttle angle is consecutivelydecreased.

Although in this embodiment four reed switches are used, it is clearthat more reed switches can be used to get a finer throttleanglethrottle voltage relationship.

It is also clear that in view of the lack of direct contact between themoving part (the rotor) linked with the throttle valve and thestationary part (the case) the durability of the switch device of thisinvention is highly improved as compared with that of potentiometers ormulticontact switches which have friction contact elements such assliding contacts or multicontact points, and that the throttle voltageproduced by the throttle voltage generating circuit comprising theswitch device of this invention is not distorted by disturbances whichare caused by vibrations transmitted from the vehicle body or the enginewhile the throttle voltage produced by the throttle voltage generatorscomprising potentiometers or multicontact switches is distorted by theabove-mentioned disturbances, since the hysteretic characteristic of thereed switches eliminates the disturbances.

Referring to FIG. the switch device 320 of this invention is, aspreviously described, a component of the throttle voltage generatingcircuit 1320 which produces the throttle voltage as shown in FIG. 4.

The vehicle speed signal is usually represented by the transmissionoutput shaft speed as previously mentioned.

A speed sensor 310 which detects the speed of the transmission outputshaft is preferably a pulse generator comprising a toothed member drivenby the transmission output shaft and an adjacent inductor pickup whichgenerates a pulse every time a tooth of the member passes the pickup sothat the frequency generated in the pickup is proportional to thetransmission output shaft speed. This frequency signal is fed to afrequency converter 1310 which produces an output voltage proportionalto the transmission output shaft speed. An example of the thus obtainedrelationship between the vehicle speed V and the transmission outputshaft voltage (vehicle speed voltage [3,) is shown in FIG. 6. Thefrequency converter 1310 comprises an amplifier, an amplitude limiter,and a frequency detecting, rectifying, and amplifying circuit. Thefrequency signal is first supplied to the amplifier in which theamplitude of the frequency signal is increased. The amplitude limiterlimits the amplitude of the signal to a fixed value, and converts theshape of the waveform of the frequency signal into a rectangularwaveform, because the rectangular waveform similar to the originalsignal waveform is maintained even after the frequency signal isamplified. The frequency detecting, rectifying, and amplifying circuitconverts the output of the amplitude limiter into a DC. voltage. Theamplifier, the amplitude limiter, and the frequency detecting,rectifying, and amplifying circuit are all of the conventional type.

A l-2 shift judge circuit 1360 consists of a l-2 shift comparisoncircuit 1330 and a 1-2 shift feedback circuit 1340. Similarly, a 2-3shift judge circuit 1460 consists of a 2-3. shift comparison circuit1430 and a 2-3 shift feedback circuit 1440. Here l-2 shifts and 2-3.shifts mean shifts between the first gear range and the second gearrange, and shifts between the second gear range and the third gearrange, respectively. A 1-2 upshift means a shift from the first gearrange to the second gear range, and a l-2 downshift means a shift fromthe second gear range to the first gear range. Similarly, a 2-3 upshiftand a 2-3 downshift mean a shift from the second gear range to the thirdgear range, and a shift from the third gear range to the second gearrange, respectively.

The throttle voltage E and the vehicle speed voltage E,, are suppliedfrom the throttle voltage generating circuit 1320 and the frequencyconverter 1310, respectively, to the judge circuits 1360 and 1460.

The 1-2 shift judge circuit 1360 has a structure as shown in FIG. 11 ofU.S. Pat. No. 3,707,097 and the description therein of circuit 1360 isincorporated herein by reference.

If the throttle voltage generating circuit including the switch deviceof this invention is used to generate the throttle voltage, the throttlevoltage oscillation never occurs due to the hysteretic characteristic ofthe reed switches even if the throttle angle hovers around each of thepredetermined throttle angles corresponding to the positions of the reedswitches. Therefore, the shift oscillation occurs in no region when thethrottle voltage generating circuit including the switch device of thisinvention is used instead of the throttle voltage generating circuitincluding the multicontact switch in the electrical control circuit togenerate the throttle voltage, because one of the two requisiteconditions for causing the shift oscillation, that is, the occurrence ofthe throttle voltage oscillation, is never met by the throttle voltagegenerating circuit including the switch device of this invention.

This matter is explained in another way by using a shift pattern diagramin terms of the vehicle speed and the throttle angle below.

If the vehicle speed V and the throttle angle 0 are substituted for thevehicle speed voltage E, and the throttle voltage E respectively, theshift pattern in terms of the vehicle speed voltage E, and the throttlevoltage E as shown in FIG. 7 is converted into a shift pattern 'in termsof the vehicle speed V and the throttle angle 0 asshown in FIG. 8. Asshown in FIG. 8, due to the hysteretic characteristic of the reedswitches the spaces along the throttle angle axis between the upshiftlines and the downshift lines appear between 0, and 0 between 0, and 0,,between 0 and 0 and between 0, and 0 When the vehicle speed ismaintained at nearly the same speed, an upshiftoccurs when the throttleangleis decreasing. Therefore, the upshift lines which are perpendicularto the throttle angle axis are located at 9 0,, 0, and 0 Similarly, thedownshift lines perpendicular to the throttle angle axis are located at0,, 9,, 0,, and 0 because the downshift occurs only when the throttleangle is increasing if the vehicle speed is maintained at nearly thesame speed. In other words, hysteresis of the reed switches lowers theupshift lines perpendicular to the throttle angle axis by the size ofhysteresis of the reed switches. If hysteresis of the switch device doesnot exist, as is the case with the multicontact switch, the spaces alongthe throttle angle axis between the upshift lines and the downshiftlines do not exist, and the upshift lines and downshift linesperpendicular to the throttle angle axis are located at the samecorresponding throttle angles: 0,, 0,, 0,, and 0 The spaces along thethrottle angle axis between the upshift lines and the downshift linesmean hysteresis between the upshift and the downshift when the vehiclespeed is maintained at nearly the same speed thereby preventingoscillation between gear ranges. Therefore, these spaces are hysteresisranges.

As shown in FIG. 8, the hysteresis ranges, which represent two gearranges according to the history of the gear ranges, intervenecontinuously and entirely between the adjacent gear range regions eachof which represents only one gear range and is not affected by thehistory of the gear ranges. This means no shift oscillation occursbetween adjacent gear ranges under any circumstances.

To provide the hysteresis ranges between the upshift lines and thedownshift lines which are perpendicular to the throttle angle axis inthe shift pattern diagram in terms of throttle angle and vehicle speedwhen the shift pattern consists of stepped shift lines can be donewithout using the switch device of this invention by providing one groupof throttle voltages for the upshifts and another group of throttlevoltages for the downshifts in an electrical control circuit for atransmission in contradistinction to the electrical control circuit ofthis invention which uses the same group of throttle voltages for theupshifts and the downshift. However, it is clear that an electricalcontrol circuit for a transmission which uses two different groups ofthrottle voltages each provided for the upshifts and for the downshiftsmust have far more complicated electronic circuits than the electricalcontrol circuit of this invention. Therefore, one advantage of theelectrical control circuit including the switch device of this invention(the electrical control circuit of this invention) is that theelectrical control circuit of this invention, notwithstanding thesirnplicity of structure thereof, always performs stable shifts howeverthe throttle angle and the vehicle speed may change.

Another characteristic of the electrical control circuit of thisinvention is, in the shift pattern diagram in terms of vehicle speed andthrottle angle, the separation of each line parallel to the throttleangle axis of the 1-2 and 2-3 upshift lines and the l-2 and 2-3downshift lines into two different kinds of branches in the regionsbetween 0, and between 0 and 0 between 0 and 0 and between 0, and 0,.

This is described in detail below.

Referring to FIG. 8, the l-2 upshift line which is designated as V =f(0) in the drawing consists of A A,, and 8 between 0 and 0,, A -A and 13-8, between 0 and 0 A -A and B B between 0 and 0 and A,-A,' and B -B,'between 0 and 0,. These separations occur due to the existence of twodifferent conditions of each applicable reed switch: one condition inwhich that particular reed switch is on, and another in which thatparticular reed switch is off.

Taking the case of the region between 0;, and 0 the two branches of theupshift lines are described below.

When the throttle angle stays between 0;, and 0 after decreasing from anangle bigger than 0 (therefore, the reed switch 5 is on, and, of course,all reed switches whose corresponding throttle angles for positioningthereof are smaller than the corresponding throttle angle of the reedswitch 5 are also on) and the vehicle speed is increasing via the routesas shown by two arrows designated as a in FIG. 8, the upshift occurs atthe shift line of A -A,'.

When the throttle angle stays between 0;, and 0 after increasing from anangle smaller than 0;, (therefore, the reed switch 5 is off, but thereed switches 4 and 3 are on) and the vehicle speed is increasing viathe routes as shown by two arrows designated as b in FIG. 8, the upshiftoccurs at the shift line B3B3'.

Similarly, taking the case of the region between 0, and 0,, the twobranches of the downshift line are described below.

When the throttle angle stays between 0, and 0 after decreasing from anangle bigger than 0., (therefore, the read switch 6 and other reedswitches whose corresponding throttle angles for positioning thereof aresmaller than the corresponding throttle angle of the reed switch 6 areon) and the vehicle speed is decreasing via the routes as shown by twoarrows designated as c in FIG. 8, the downshift occurs at the shift lineof C4-C4I.

When the throttle angle stays between 0 and 0 after increasing from anangle smaller than 0, (therefore, the reed switch 6 is off, but otherreed switches whose corresponding throttle angles for positioningthereof are smaller than the corresponding throttle angle of the reedswitch 6 are on) and the vehicle speed is decreasing via the routes asshown by two arrows designated as d in FIG. 8, the downshift occurs atthe shift line of D,D

If hysteresis of the switch device does not exist, as is the case withthe multicontact switch, all the l-2 upshifts and l-2 downshifts in theregion between 0, and 0,, between 0, and 0,, between 0 and 0 and between0 and 0, occur at the lines of B B,, B B B,,,;', and B,B, only, and atthe lines of D,-D D,D D -D and D D., only, respectively.

The same description as made for the l-2 upshift line V=f (0) and the1-2 downshift line V=f,'(0) is applied to the 2-3 upshift linedesignated as V =f, (0) in FIG. 8 and the 2-3 downshift line designatedas V=f,( 0) in the same drawing.

For clarification, domains of the control and the electrical controlcircuit are defined below.

A three forward speed transmission controlled by the control of thisinvention comprises a torque converter, a planetary gear set, atransmission output shaft, and the control, wherein the controlcomprises an electrical control circuit, two hydraulic shift valves, twoclutches, and two brakes, wherein the electrical control circuitcomprises a throttle position signal generator, a vehicle speed signalgenerator, two solenoids, and two shift judge circuits comprising twocomparison circuits and two feedback circuits.

It is claimed: 1

1. In an engine having throttle means, apparatus for generating avoltage corresponding to the position of said throttle means,comprising, in combination: magnetic means operatively associated withsaid throttle means; circuit means including a plurality of switch meansand having an output terminal for supplying said voltage and changingthe value thereof ina continuous stepped way when any one of said switchmeans is closed; said switch means being disposed in spaced relationshipto each other and to said magnetic means; said switch means being closedby being energized by said magnetic means.

2. Apparatus according to claim 1, wherein said magnetic means comprisesa rotatable member coupled to said throttle means, and a magnet coupledto said member for rotation therewith; said switch means being disposedradially about the axis of rotation of said rotatable member atpredetermined angles with respect to each other; said magnet beingrotatable by said throttle means through each of said predeterminedangles in turn in each of first and second directions; and wherein eachswitch means disposed at each angle through which said magnet has beenmoved in said first direction by said throttle means remains energizeduntil said magnet has been moved in said second direction through saideach angle, said each switch means thereafter being de-energized inturn.

3. Apparatus as recited in claim 1, wherein each of said switch meanshas a predetermined angle assigned thereto, each of said switch meansbeing disposed relative to said magnetic means so as to be energizedwhen a throttle angle as measured from a fully closed position of saidthrottle means becomes said predetermined angle, said magnetic meansbeing designed so as to energize all of said switch means whose saidpredetermined angles are smaller than said throttle angle.

4. Apparatus as recited in claim 3, wherein said circuit means furthercomprises: a plurality of impedance elements each of which is connectedin series with each one of said switch means to make a set of seriescombinations of one of said switch means and one of said impedanceelements; an additional impedance element; and a source of electricalenergy; each of said series combinations being connected in parallelwith other of said series combinations to make a parallel combination;one terminal of said parallel combination being connected to oneterminal of said electrical energy source, a second terminal of saidparallel combination being connected with one terminal of saidadditional impedance element, a second terminal of said additionalimpedance element being connected to a second terminal of saidelectrical energy source; said output terminal being connected with saidparallel combination second terminal.

5. Apparatus as recited in claim 4, further comprising a furtherimpedance element connected across said parallel combination.

6. Apparatus as recited in claim 4, wherein each of said switch means isde-energized when said throttle angle becomes an angle smaller than saidpredetermined angle assigned to each of said switch means.

7. Apparatus as recited in claim 5, wherein each of said switch means isde-energized when said throttle angle becomes an angle smaller than saidpredetermined angle assigned to each of said switch means.

8. Apparatus connected with a source of electrical energy for generatinga voltage corresponding to throttle position of an engine havingthrottle means, comprising, in combination: magnetic means operativelyassociated with said throttle means; a plurality of switch means; aplurality of impedance elements each of which is connected in serieswith each one of said switch means to make a set of series combinationsof one of said switch means and one of said impedance elements; anadditional impedance element; and an output terminal for supplying saidvoltage; each of said series combinations being connected in parallelwith other of said series combinations to make a parallel comination;one terminal of said parallel combination being connected to oneterminal of said electrical energy source, a second terminal of saidparallel combination being connected with one terminal of saidadditional impedance element, a second terminal of said additionalimpedance element being connected to a second terminal of saidelectrical energy source; said output terminal being connected with saidparallel combination second terminal; each of said switch means having apredetermined angle assigned thereto, each of said switch means beingdisposed relative to said magnetic means so as to be energized when athrottle angle as measured from a fully closed position of said throttlemeans becomes said predetermined angle; said switch means being closedwhen said switch means is energized by said magnetic means; saidmagnetic means being designed so as to energize all of said switch meanswhose said predetermined angles are smaller than said throttle angle;each of said switch means being de-energized when said throttle anglebecomes an angle smaller than said predetermined angle assigned to eachof said switch means.

9. Apparatus as recited in claim 8, further comprising a furtherimpedance element connected across said parallel combination.

1. In an engine having throttle means, apparatus for generating avoltage corresponding to the position of said throttle means,comprising, in combination: magnetic means operatively associated withsaid throttle means; circuit means including a plurality of switch meansand having an output terminal for supplying said voltage and changingthe value thereof in a continuous stepped way when any one of saidswitch means is closed; said switch means being disposed in spacedrelationship to each other and to said magnetic means; said switch meansbeing closed by being energized by said magnetic means.
 2. Apparatusaccording to claim 1, wherein said magnetic means comprises a rotatablemember coupled to said throttle means, and a magnet coupled to saidmember for rotation therewith; said switch means being disposed radiallyabout the axis of rotatIon of said rotatable member at predeterminedangles with respect to each other; said magnet being rotatable by saidthrottle means through each of said predetermined angles in turn in eachof first and second directions; and wherein each switch means disposedat each angle through which said magnet has been moved in said firstdirection by said throttle means remains energized until said magnet hasbeen moved in said second direction through said each angle, said eachswitch means thereafter being de-energized in turn.
 3. Apparatus asrecited in claim 1, wherein each of said switch means has apredetermined angle assigned thereto, each of said switch means beingdisposed relative to said magnetic means so as to be energized when athrottle angle as measured from a fully closed position of said throttlemeans becomes said predetermined angle, said magnetic means beingdesigned so as to energize all of said switch means whose saidpredetermined angles are smaller than said throttle angle.
 4. Apparatusas recited in claim 3, wherein said circuit means further comprises: aplurality of impedance elements each of which is connected in serieswith each one of said switch means to make a set of series combinationsof one of said switch means and one of said impedance elements; anadditional impedance element; and a source of electrical energy; each ofsaid series combinations being connected in parallel with other of saidseries combinations to make a parallel combination; one terminal of saidparallel combination being connected to one terminal of said electricalenergy source, a second terminal of said parallel combination beingconnected with one terminal of said additional impedance element, asecond terminal of said additional impedance element being connected toa second terminal of said electrical energy source; said output terminalbeing connected with said parallel combination second terminal. 5.Apparatus as recited in claim 4, further comprising a further impedanceelement connected across said parallel combination.
 6. Apparatus asrecited in claim 4, wherein each of said switch means is de-energizedwhen said throttle angle becomes an angle smaller than saidpredetermined angle assigned to each of said switch means.
 7. Apparatusas recited in claim 5, wherein each of said switch means is de-energizedwhen said throttle angle becomes an angle smaller than saidpredetermined angle assigned to each of said switch means.
 8. Apparatusconnected with a source of electrical energy for generating a voltagecorresponding to throttle position of an engine having throttle means,comprising, in combination: magnetic means operatively associated withsaid throttle means; a plurality of switch means; a plurality ofimpedance elements each of which is connected in series with each one ofsaid switch means to make a set of series combinations of one of saidswitch means and one of said impedance elements; an additional impedanceelement; and an output terminal for supplying said voltage; each of saidseries combinations being connected in parallel with other of saidseries combinations to make a parallel comination; one terminal of saidparallel combination being connected to one terminal of said electricalenergy source, a second terminal of said parallel combination beingconnected with one terminal of said additional impedance element, asecond terminal of said additional impedance element being connected toa second terminal of said electrical energy source; said output terminalbeing connected with said parallel combination second terminal; each ofsaid switch means having a predetermined angle assigned thereto, each ofsaid switch means being disposed relative to said magnetic means so asto be energized when a throttle angle as measured from a fully closedposition of said throttle means becomes said predetermined angle; saidswitch means being closed when said switch means is energized by saidmagnetic means; said magnetic means being designed so as to energiZe allof said switch means whose said predetermined angles are smaller thansaid throttle angle; each of said switch means being de-energized whensaid throttle angle becomes an angle smaller than said predeterminedangle assigned to each of said switch means.
 9. Apparatus as recited inclaim 8, further comprising a further impedance element connected acrosssaid parallel combination.